From 70fb85cd4aee6cd4991c64b91b842b9be79ad6b1 Mon Sep 17 00:00:00 2001
From: prathamesh0 <prathamesh.musale0@gmail.com>
Date: Thu, 7 Jul 2022 11:11:45 +0530
Subject: [PATCH] Fetch transaction by hash in a single query

---
 pkg/eth/backend.go | 62 ++++++++++++++--------------------------------
 1 file changed, 19 insertions(+), 43 deletions(-)

diff --git a/pkg/eth/backend.go b/pkg/eth/backend.go
index 77b5664e..a5a8e34c 100644
--- a/pkg/eth/backend.go
+++ b/pkg/eth/backend.go
@@ -52,11 +52,11 @@ import (
 )
 
 var (
-	errPendingBlockNumber  = errors.New("pending block number not supported")
-	errNegativeBlockNumber = errors.New("negative block number not supported")
-	errHeaderHashNotFound  = errors.New("header for hash not found")
-	errHeaderNotFound      = errors.New("header not found")
-	errTxHashNotFound      = errors.New("transaction for hash not found")
+	errPendingBlockNumber     = errors.New("pending block number not supported")
+	errNegativeBlockNumber    = errors.New("negative block number not supported")
+	errHeaderHashNotFound     = errors.New("header for hash not found")
+	errHeaderNotFound         = errors.New("header not found")
+	errTxHashInMultipleBlocks = errors.New("transaction for hash found in more than one canonical block")
 
 	// errMissingSignature is returned if a block's extra-data section doesn't seem
 	// to contain a 65 byte secp256k1 signature.
@@ -72,15 +72,12 @@ const (
 									WHERE block_hash = (SELECT canonical_header_hash($1))`
 	RetrieveTD = `SELECT CAST(td as Text) FROM eth.header_cids
 			WHERE header_cids.block_hash = $1`
-	RetrieveBlocksByTxHash = `SELECT block_number, header_id FROM from eth.transaction_cids
-			WHERE tx_hash = $1`
-	RetrieveRPCTransaction = `SELECT blocks.data, index
-			FROM public.blocks, eth.transaction_cids, eth.header_cids
+	RetrieveRPCTransaction = `SELECT blocks.data, header_id, transaction_cids.block_number, index
+			FROM public.blocks, eth.transaction_cids
 			WHERE blocks.key = transaction_cids.mh_key
 			AND blocks.block_number = transaction_cids.block_number
 			AND transaction_cids.tx_hash = $1
-			AND transaction_cids.header_id = $2
-			AND transaction_cids.block_number = $3`
+			AND transaction_cids.header_id = (SELECT canonical_header_hash(transaction_cids.block_number))`
 	RetrieveCodeHashByLeafKeyAndBlockHash = `SELECT code_hash FROM eth.state_accounts, eth.state_cids, eth.header_cids
 											WHERE state_accounts.header_id = state_cids.header_id
 											AND state_accounts.state_path = state_cids.state_path
@@ -522,49 +519,28 @@ func (b *Backend) BlockByHash(ctx context.Context, hash common.Hash) (*types.Blo
 // GetTransaction retrieves a tx by hash
 // It also returns the blockhash, blocknumber, and tx index associated with the transaction
 func (b *Backend) GetTransaction(ctx context.Context, txHash common.Hash) (*types.Transaction, common.Hash, uint64, uint64, error) {
-	type txBlock struct {
-		BlockNumber uint64 `db:"block_number"`
+	type txRes struct {
+		Data        []byte `db:"data"`
 		HeaderID    string `db:"header_id"`
+		BlockNumber uint64 `db:"block_number"`
+		Index       uint64 `db:"index"`
 	}
-
-	// get number and hash of blocks having the given txHash
-	txBlockRes := make([]txBlock, 0)
-	if err := b.DB.Select(&txBlockRes, RetrieveBlocksByTxHash, txHash.String()); err != nil {
+	var res = make([]txRes, 0)
+	if err := b.DB.Get(&res, RetrieveRPCTransaction, txHash.String()); err != nil {
 		return nil, common.Hash{}, 0, 0, err
 	}
 
-	// filter out non-canonical blocks
-	var canonicalTxBlock txBlock
-	for _, res := range txBlockRes {
-		canonicalHash, err := b.GetCanonicalHash(res.BlockNumber)
-		if err != nil {
-			return nil, common.Hash{}, 0, 0, err
-		}
-
-		if res.HeaderID == canonicalHash.String() {
-			canonicalTxBlock = res
-			break
-		}
-	}
-
-	if canonicalTxBlock == (txBlock{}) {
-		return nil, common.Hash{}, 0, 0, errTxHashNotFound
-	}
-
-	var tempTxStruct struct {
-		Data  []byte `db:"data"`
-		Index uint64 `db:"index"`
-	}
-	if err := b.DB.Get(&tempTxStruct, RetrieveRPCTransaction, txHash.String(), canonicalTxBlock.HeaderID, canonicalTxBlock.BlockNumber); err != nil {
-		return nil, common.Hash{}, 0, 0, err
+	// a transaction can be part of a only one canonical block
+	if len(res) > 1 {
+		return nil, common.Hash{}, 0, 0, errTxHashInMultipleBlocks
 	}
 
 	var transaction types.Transaction
-	if err := transaction.UnmarshalBinary(tempTxStruct.Data); err != nil {
+	if err := transaction.UnmarshalBinary(res[0].Data); err != nil {
 		return nil, common.Hash{}, 0, 0, err
 	}
 
-	return &transaction, common.HexToHash(canonicalTxBlock.HeaderID), canonicalTxBlock.BlockNumber, tempTxStruct.Index, nil
+	return &transaction, common.HexToHash(res[0].HeaderID), res[0].BlockNumber, res[0].Index, nil
 }
 
 // GetReceipts retrieves receipts for provided block hash